Portion of a display screen with a graphical user interface



FIG. 1 is a front elevational view of the portion of a display screen with a graphical user interface showing our new design; and,

FIG. 2 is a front elevational view of another embodiment of the portion of a display screen with a graphical user interface our new design.

The small broken lines within the graphical user interface and the large dash-dot-dash lines showing the portion of the display screen form no part of the claimed design. 

CLAIM The ornamental design for a portion of a display screen with a graphical user interface, as shown and described. 